Rolling cone earth boring bits have been used for many years for drilling wells. The bit has a body with at least one leg, usually three. A bearing pin depends from each bit leg, extending inward and downward toward the axis of rotation of the bit body. A cone with teeth on its exterior mounts rotatably to each bearing pin.
The cone has a cavity that fits over the bearing pin. The cavity has an entrance portion or mouth adjacent the junction of the bit leg and the bearing pin. A seal is located at the entrance to seal the cavity form cuttings and drilling mud. Most well drilling rolling cone bits are filled with a lubricant that is sealed by the seal at the cavity mouth.
Many different seals have been used in the past as well as today. One type has a rigid seal ring that extends around the bearing pin and is urged by an elastomeric energizer ring into sliding engagement with a seal face in the cone cavity. The seal face rotates with the cone, while the seal ring and energizer ring are stationary with the bearing pin. An elastomeric excluder ring may be located between the bit leg and the outer ends of the energizer ring for keeping drilling mud and cuttings from the seal. While successful, sometimes mud packing occurs at the seal, causing damages to the seal.